The present invention relates to a scanning exposure photo-mask, and a scanning exposure system as well as a method of scanning an exposure beam by a scanning exposure system.
Variation in width of the line-shaped patterns over a chip is due to the coma in the projection lens such as a reduced projection lens. The coma is caused by a displacement in focusing position between a light transmitted through an optical axis of a reducing projecting lens and an oblique light transmitted at an oblique angle to the optical axis through the reducing projecting lens. As the incident angle to the optical axis is increased, the displacement in focusing position is also increased, whereby a blooming appears. The influence of coma is larger on opposite ends in the longitudinal direction of the line-shaped pattern due to a larger distance from the optical axis than the influence of coma on opposite sides in the width direction of the line-shaped pattern. If the exposure light beam defined by the slit is scanned in a longitudinal direction of the line-shaped pattern, then the influence of coma is larger on opposite ends in the longitudinal direction of the line-shaped pattern due to a larger distance from the optical axis than the influence of coma on opposite sides in the width direction of the line-shaped pattern. This influence of coma prevents a highly accurate exposure and a dimension of the exposure pattern is deteriorated. The center region pattern has no variation in actual dimension from the predetermined dimension. The peripheral region pattern is reduced in width from the predetermined width.
Accordingly, it is an object of the present invention to provide a novel scanning exposure photo-mask free from any substantive influence of coma.
It is a further object of the present invention to provide a novel scanning exposure system free from any substantive influence of coma.
It is a still further object of the present invention to provide a novel method of scanning an exposure beam by a scanning exposure system free from any substantive influence of coma.
The present invention provides a scanning exposure photo-mask having an exposure pattern which has a longitudinal direction. The scanning exposure photo-mask is placed in an exposure system so that the longitudinal direction of the pattern is parallel to a longitudinal direction of a slit of the exposure system.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.